In 2022, the U.S. Geological Survey (USGS) in cooperation with the New Hampshire Department of Transportation (NHDOT) made 107 horizontal-to-vertical spectral ratio (HVSR) passive seismic geophysical measurements at four transportation infrastructure sites in New Hampshire to determine the benefits of HVSR as an enhancement to traditional geotechnical site characterizations performed by NHDOT. Typically, data are obtained from the subsurface during borings to characterize geotechnical properties but often borings are spaced hundreds of feet apart. Geotechnical site characterization guided by geophysical surveys (such as the HVSR method) between borings will help provide a more thorough characterization. By combining analysis of geophysical and boring data, transportation projects can produce a more comprehensive representation of geotechnical subsurface conditions than can be determined using conventional borings alone. The HVSR method measures the resonance frequency (f0) induced by ambient seismic noise in unconsolidated sediments overlying bedrock when there is a substantial contrast in shear-wave acoustic impedance between the two layers (> 2:1). Spectral ratio analysis of the horizontal and vertical components of the seismic data is used to determine f0. Overburden thickness can be related to f0 with thicker overburden related to lower frequencies, and higher frequencies with thinner overburden. A three-component seismometer was used to measure the vertical and horizontal components of ambient seismic noise using the HVSR method. This data release contains raw HVSR data and measurement locations.

In June 2018, U.S. Geological Survey (USGS) in cooperation with the U.S. Environmental Protection Agency (EPA) collected geophysical measurements to help evaluate the suitability of a proposed landfill site for disposing mine-waste materials in Fredericktown, MO. A total of 35 horizontal-to-vertical spectral ratio (HVSR) passive seismic measurements were collected at the site. The HVSR technique uses a three-component seismometer to measure the vertical and horizontal components of ambient seismic noise. Seismic noise in the range of approximately 0.1 to 1 Hertz (Hz) is caused by ocean waves, large regional storms, and tectonic sources. A resonance frequency (f0) is induced in the unconsolidated sediments when there is a substantial contrast (greater than 2 to 1 ratio) in shear-wave acoustic impedance between the overburden and the bedrock. The HVSR data were interpreted to determine the f0 from analysis of the spectral ratio of the horizontal and vertical components of the seismic data. The thickness of the overburden can be related to f0. In general, lower f0 relates to thicker sediments, and higher f0 relates to relatively thinner overburden. At the Fredericktown, MO, site the resonance frequency was related to the depth of the overburden using an average shear-wave velocity that was measured at the site using active seismic source measurements. About two thirds of the HVSR surveys exhibited low to zero amplitude peaks, which is consistent with either a low amplitude acoustic impedance, an overburden layer, or a combination of both that is too thin to measure. The median value of the depth to bedrock for the 10 reliable measurements was 1.6 meters.

In 2022, the U.S. Geological Survey (USGS) New England Water Science Center, in cooperation with the New Hampshire Department of Transportation (NHDOT), surveyed four transportation infrastructure sites with frequency-domain electromagnetic induction (EMI) instruments and one site with ground-penetrating radar (GPR) to aid traditional geotechnical site characterizations performed by NHDOT. Information about subsurface physical properties is typically obtained through the use of borings during geotechnical site characterizations. Geotechnical site investigations that also include geophysical surveys (such as the EMI and GPR methods) between borings help provide more thorough characterizations. Integrated analysis of geophysical and boring data for transportation projects aids in the production of a more spatially comprehensive representation of geotechnical subsurface conditions than can be determined using conventional borings alone. Two frequency-domain EMI instruments that measure electrical conductivity changes with depth in different ways were used: ·The GEM-2 (serial number 405, Geophex, Ltd.), with fixed transmitter-receiver (Tx-Rx) coil spacing, transmits waves at several logarithmically spaced frequencies (1530Hz, 3930Hz, 8250Hz, 13590Hz, 20370Hz, and 47970Hz). Lower frequencies are generally capable of imaging deeper, and higher frequencies provide increased resolution of the subsurface. · The DUALEM-421 (serial number 335, DualEM, Inc.) uses a single frequency at 9-kHz with various Tx-Rx coil spacings and orientations, where larger coil spacings image deeper and shorter coil spacings provide increased resolution of the subsurface. Ground penetrating radar profiles used an antenna with a fixed Tx-Rx offset contained within a tow-body. GPR transmits pulses of electromagnetic energy into the subsurface and records the amplitude and timing for the return of reflected signals (Keary and Brooks, 1991). The GPR data were collected using a MALA GX controller (ID:227603071) running software version 15.2.269.39 and GroundExplorer 80-MHz shielded antenna (ID:1513002). This data release contains raw and processed EMI and GPR data and measurement locations. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government. The data provided in this data release are: (1) raw GPR profile data in the *.RD3 and *.RD7 formats, (2) raw DUALEM-421 data in comma separated values (*.CSV) files, (3) raw GEM-2 data in Geophex Binary Format (*.GBF), and *.CSV file formats (Geophex software application, EMExport (Version 4.5.2) was used to export the raw binary *.GBF format to *.CSV), (4) processed DUALEM and GEM-2 files with ‘_dat’ in the filename, and (5) inverted DUALEM and GEM-2 profiles with ‘_inv’ in the filename. Readme files are available to explain the data contained within the data files References: Kearey, P., and Brooks, M., 1991, An introduction to geophysical exploration second edition: Blackwell Scientific Publications, Cambridge, Mass., 254p.

The horizontal-to-vertical spectral ratio (HVSR) method is a passive seismic technique that uses a three-component seismometer to measure the vertical and horizontal components of ambient seismic noise. Seismic noise in the range of ~0.1 to 1 Hertz (Hz) is caused by ocean waves, large regional storms, and tectonic sources. A resonance frequency (f0) is induced in the unconsolidated when there is a substantial contrast (greater than 2:1) in shear-wave acoustic impedance between the overburden and the bedrock. The f0 is determined from the analysis of the spectral ratio of the horizontal and vertical components of the seismic data. The thickness of the overburden can be related to the f0. In general, lower f0 relates to thicker sediments, and higher f0 relates to relatively thinner overburden. At the former Callahan MIne site the resonance frequency can be related to the depth of the overburden using an average shear-wave velocity that is measured or estimated from locations where there is a known depth to rock and/or using a direct measurement of the shear-wave velocity.

This dataset contains passive seismic data collected using a three-component seismometer during 2018-2020 at Pinnacles National Park, California. The data were acquired for the purpose of estimating depth to the bedrock surface underlying alluvial deposits, using the horizontal-to-vertical spectral ratio (HVSR) technique. Data were collected along ten transects, with 3 to 14 points collected along each transect, and at the locations of 6 existing or abandoned wells. A total of 81 passive seismic measurements were collected and the raw data are included in this dataset. The passive seismic data record ambient seismic noise in the range of approximately 0.1 to 1 Hertz (Hz), which is caused by ocean waves, large regional storms, and tectonic sources. The HVSR method analyzes the spectral ratio of the vertical and horizontal components of the passive seismic data to determine the fundamental seismic resonance frequency (f0), which is induced in unconsolidated sediments when there is a substantial contrast (greater than 2 to 1 ratio) in shear-wave acoustic impedance between these sediments and the bedrock. The thickness of the sediments is a function of f0.

In summer 2018, a total of 43 passive seismic surveys were conducted in the Des Moines River floodplain. The horizontal-to-vertical spectral ratio (HVSR) method is a passive seismic technique that uses a three-component seismometer to measure the vertical and horizontal components of ambient seismic noise. A resonance frequency (f0) is induced in the unconsolidated deposits when there is a substantial contrast (greater than 2:1) in shear-wave acoustic impedance between the overburden and the bedrock. The f0 is determined from the analysis of the spectral ratio of the horizontal and vertical components of the seismic data. The thickness of the overburden can be related to the f0. In general, lower f0 relates to thicker sediments, and higher f0 relates to relatively thinner overburden. This data release contains a text file (Readme_HVSR.txt) that explains data files and processing references, 6 .zip folders 5 related to survey line(s) on a given date and one for individual measurements not related to survey lines with each zip folder containing measurement site folders and original data files and resultant measurement report (.trc, .saf or .dat, and .doc) , a notes file for archiving surface-geophysical data (HVSR_Archive_Notes_DesMoinesIA.csv), and another comma-separated values file (HVSR_Index_DesMoinesIA.csv) that can be used to help navigate the data files. Field notes taken at the time of data collection are not included in this data release but are available upon request.

Passive seismic data collection was done northwest of the Air Force Research Laboratory (AFRL) at Edwards Air Force Base using the horizontal-to-vertical spectral ratio (HVSR) technique. HVSR surveys were done at 43 locations between May and September 2018 to refine the understanding of the bedrock-alluvial aquifer transition zone downgradient from the AFRL. Specifically, the data were collected to help determine the depth to bedrock. The HVSR method is a passive seismic technique that uses a three-component seismometer to measure the vertical and horizontal components of ambient seismic noise. Seismic noise in the range of ~0.1 to 1 Hertz (Hz) is caused by ocean waves, large regional storms, and tectonic sources. A resonance frequency (f0) is induced in unconsolidated alluvium when there is a substantial contrast (greater than 2:1) in shear-wave acoustic impedance between the alluvial overburden and the bedrock. The f0 is determined from the analysis of the spectral ratio of the horizontal and vertical components of the seismic data. The thickness of the overburden can be related to the f0. In general, lower f0 relates to thicker sediments, and higher f0 relates to relatively thinner overburden. Other geophysical techniques–including time-domain electromagnetics and electrical resistivity tomography–co-located with the HVSR data are made available in other child pages within this data release: https://doi.org/10.5066/P9ZGZTA4HVSR. This page contains the raw HVSR data.

Passive seismic data collection was done northwest of the Air Force Research Laboratory (AFRL) at Edwards Air Force Base using the horizontal-to-vertical spectral ratio (HVSR) technique. HVSR surveys were done at 43 locations between May and September 2018 to refine the understanding of the bedrock-alluvial aquifer transition zone downgradient from the AFRL. Specifically, the data were collected to help determine the depth to bedrock. The HVSR method is a passive seismic technique that uses a three-component seismometer to measure the vertical and horizontal components of ambient seismic noise. Seismic noise in the range of ~0.1 to 1 Hertz (Hz) is caused by ocean waves, large regional storms, and tectonic sources. A resonance frequency (f0) is induced in unconsolidated alluvium when there is a substantial contrast (greater than 2:1) in shear-wave acoustic impedance between the alluvial overburden and the bedrock. The f0 is determined from the analysis of the spectral ratio of the horizontal and vertical components of the seismic data. The thickness of the overburden can be related to the f0. In general, lower f0 relates to thicker sediments, and higher f0 relates to relatively thinner overburden. Other geophysical techniques–including time-domain electromagnetics and electrical resistivity tomography–co-located with the HVSR data are made available in other child pages within this data release: https://doi.org/10.5066/P9ZGZTA4HVSR. This page contains the raw HVSR data.

In June 2018, the U.S. Geological Survey (USGS) in cooperation with the U.S. Environmental Protection Agency (EPA) collected geophysical measurements to help evaluate the suitability of a proposed landfill site for disposing mine-waste materials in Fredericktown, Missouri. Geophysical methods were used to evaluate and characterize the unconsolidated sediment (i.e., regolith) above the crystalline bedrock as well as determine depth bedrock. Land-based geophysical methods included frequency domain electromagnetic induction (FDEM), electrical resistivity tomography (ERT), horizontal-to-vertical spectral ratio passive seismic (HVSR), and shear-wave seismic refraction. Water-borne methods included FDEM surveys to characterize the Fredericktown City Lake sediments as well as forward-looking infrared (FLIR) imagery taken along the City Lake shoreline to identify locations of potential groundwater-surface water interactions.